Seasonal vaccination with RTS,S/AS01E vaccine with or without seasonal malaria chemoprevention in children up to the age of 5 years in Burkina Faso and Mali: a double-blind, randomised, controlled, phase 3 trial
Authors: Alassane Dicko, Jean-Bosco Ouedraogo, Issaka Zongo, Issaka Sagara, Matthew Cairns, Rakiswendé Serge Yerbanga, Djibrilla Issiaka, Charles Zoungrana, Youssoufa Sidibe, Amadou Tapily, Frédéric Nikièma, Frédéric Sompougdou, Koualy Sanogo, Mahamadou Kaya, Hama Yalcouye, Oumar Mohamed Dicko, Modibo Diarra, Kalifa Diarra, Ismaila Thera, Alassane Haro, Abdoul Aziz Sienou, Seydou Traore, Almahamoudou Mahamar, Amagana Dolo, Irene Kuepfer, Paul Snell, Jane Grant, Jayne Webster, Paul Milligan, Cynthia Lee, Christian Ockenhouse, Opokua Ofori-Anyinam, Halidou Tinto, Abdoulaye Djimde, Daniel Chandramohan, Brian Greenwood
Journal: The Lancet Infectious Diseases (2023)

<h2>Summary</h2><h3>Background</h3> Seasonal vaccination with the RTS,S/AS01<sub>E</sub> vaccine combined with seasonal malaria chemoprevention (SMC) prevented malaria in young children more effectively than either intervention given alone over a 3 year period. The objective of this study was to establish whether the added protection provided by the combination could be sustained for a further 2 years. <h3>Methods</h3> This was a double-blind, individually randomised, controlled, non-inferiority and superiority, phase 3 trial done at two sites: the Bougouni district and neighbouring areas in Mali and Houndé district, Burkina Faso. Children who had been enrolled in the initial 3-year trial when aged 5–17 months were initially randomly assigned individually to receive SMC with sulphadoxine-pyrimethamine and amodiaquine plus control vaccines, RTS,S/AS01<sub>E</sub> plus placebo SMC, or SMC plus RTS,S/AS01<sub>E</sub>. They continued to receive the same interventions until the age of 5 years. The primary trial endpoint was the incidence of clinical malaria over the 5-year trial period in both the modified intention-to-treat and per-protocol populations. Over the 5-year period, non-inferiority was defined as a 20% increase in clinical malaria in the RTS,S/AS01<sub>E</sub>-alone group compared with the SMC alone group. Superiority was defined as a 12% difference in the incidence of clinical malaria between the combined and single intervention groups. The study is registered with ClinicalTrials.gov, NCT04319380, and is complete. <h3>Findings</h3> In April, 2020, of 6861 children originally recruited, 5098 (94%) of the 5433 children who completed the initial 3-year follow-up were re-enrolled in the extension study. Over 5 years, the incidence of clinical malaria per 1000 person-years at risk was 313 in the SMC alone group, 320 in the RTS,S/AS01<sub>E</sub>-alone group, and 133 in the combined group. The combination of RTS,S/AS01<sub>E</sub> and SMC was superior to SMC (protective efficacy 57·7%, 95% CI 53·3 to 61·7) and to RTS,S/AS01<sub>E</sub> (protective efficacy 59·0%, 54·7 to 62·8) in preventing clinical malaria. RTS,S/AS01<sub>E</sub> was non-inferior to SMC (hazard ratio 1·03 [95% CI 0·95 to 1·12]). The protective efficacy of the combination versus SMC over the 5-year period of the study was very similar to that seen in the first 3 years with the protective efficacy of the combination versus SMC being 57·7% (53·3 to 61·7) and versus RTS/AS01<sub>E</sub>-alone being 59·0% (54·7 to 62·8). The comparable figures for the first 3 years of the study were 62·8% (58·4 to 66·8) and 59·6% (54·7 to 64·0%), respectively. Hospital admissions for WHO-defined severe malaria were reduced by 66·8% (95% CI 40·3 to 81·5), for malarial anaemia by 65·9% (34·1 to 82·4), for blood transfusion by 68·1% (32·6 to 84·9), for all-cause deaths by 44·5% (2·8 to 68·3), for deaths excluding external causes or surgery by 41·1% (−9·2 to 68·3), and for deaths from malaria by 66·8% (−2·7 to 89·3) in the combined group compared with the SMC alone group. No safety signals were detected. <h3>Interpretation</h3> Substantial protection against malaria was sustained over 5 years by combining seasonal malaria vaccination with seasonal chemoprevention, offering a potential new approach to malaria control in areas with seasonal malaria transmission. <h3>Funding</h3> UK Joint Global Health Trials and PATH's Malaria Vaccine Initiative (through a grant from the Bill & Melinda Gates Foundation). <h3>Translation</h3> For the French translation of the abstract see Supplementary Materials section.